[VPlan] Allow setting IR name for VPDerivedIVRecipe (NFCI).

Allow setting the name to use for the generated IR value of the derived
IV in preparations for #112145.

This is analogous to VPInstruction::Name.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h

@@ -234,9 +234,9 @@ class VPBuilder {
   VPDerivedIVRecipe *createDerivedIV(InductionDescriptor::InductionKind Kind,
                                      FPMathOperator *FPBinOp, VPValue *Start,
                                      VPCanonicalIVPHIRecipe *CanonicalIV,
-                                     VPValue *Step) {
+                                     VPValue *Step, const Twine &Name = "") {
     return tryInsertInstruction(
-        new VPDerivedIVRecipe(Kind, FPBinOp, Start, CanonicalIV, Step));
+        new VPDerivedIVRecipe(Kind, FPBinOp, Start, CanonicalIV, Step, Name));
   }
 
   VPScalarCastRecipe *createScalarCast(Instruction::CastOps Opcode, VPValue *Op,

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -9603,7 +9603,7 @@ void VPDerivedIVRecipe::execute(VPTransformState &State) {
   Value *DerivedIV = emitTransformedIndex(
       State.Builder, CanonicalIV, getStartValue()->getLiveInIRValue(), Step,
       Kind, cast_if_present<BinaryOperator>(FPBinOp));
-  DerivedIV->setName("offset.idx");
+  DerivedIV->setName(Name);
   assert(DerivedIV != CanonicalIV && "IV didn't need transforming?");
 
   State.set(this, DerivedIV, VPLane(0));

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -3301,19 +3301,23 @@ class VPDerivedIVRecipe : public VPSingleDefRecipe {
   /// for floating point inductions.
   const FPMathOperator *FPBinOp;
 
+  /// Name to use for the generated IR instruction for the derived IV.
+  std::string Name;
+
 public:
   VPDerivedIVRecipe(const InductionDescriptor &IndDesc, VPValue *Start,
-                    VPCanonicalIVPHIRecipe *CanonicalIV, VPValue *Step)
+                    VPCanonicalIVPHIRecipe *CanonicalIV, VPValue *Step,
+                    const Twine &Name = "")
       : VPDerivedIVRecipe(
             IndDesc.getKind(),
             dyn_cast_or_null<FPMathOperator>(IndDesc.getInductionBinOp()),
-            Start, CanonicalIV, Step) {}
+            Start, CanonicalIV, Step, Name) {}
 
   VPDerivedIVRecipe(InductionDescriptor::InductionKind Kind,
                     const FPMathOperator *FPBinOp, VPValue *Start, VPValue *IV,
-                    VPValue *Step)
+                    VPValue *Step, const Twine &Name = "")
       : VPSingleDefRecipe(VPDef::VPDerivedIVSC, {Start, IV, Step}), Kind(Kind),
-        FPBinOp(FPBinOp) {}
+        FPBinOp(FPBinOp), Name(Name.str()) {}
 
   ~VPDerivedIVRecipe() override = default;
 

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -528,7 +528,8 @@ createScalarIVSteps(VPlan &Plan, InductionDescriptor::InductionKind Kind,
   VPCanonicalIVPHIRecipe *CanonicalIV = Plan.getCanonicalIV();
   VPSingleDefRecipe *BaseIV = CanonicalIV;
   if (!CanonicalIV->isCanonical(Kind, StartV, Step)) {
-    BaseIV = Builder.createDerivedIV(Kind, FPBinOp, StartV, CanonicalIV, Step);
+    BaseIV = Builder.createDerivedIV(Kind, FPBinOp, StartV, CanonicalIV, Step,
+                                     "offset.idx");
   }
 
   // Truncate base induction if needed.

llvm/test/Transforms/LoopVectorize/branch-weights.ll

@@ -18,7 +18,7 @@
 ; CHECK:   br label %vector.body
 ;
 ; CHECK: vector.body:
-; CHECK:   br i1 %8, label %middle.block, label %vector.body, !prof [[PROF_F0_VECTOR_BODY:![0-9]+]]
+; CHECK:   br i1 {{.+}}, label %middle.block, label %vector.body, !prof [[PROF_F0_VECTOR_BODY:![0-9]+]]
 ;
 ; CHECK: middle.block:
 ; CHECK:   br i1 %cmp.n, label %exit.loopexit, label %vec.epilog.iter.check, !prof [[PROF_F0_MIDDLE_BLOCKS:![0-9]+]]
@@ -30,10 +30,10 @@
 ; CHECK:   br label %vec.epilog.vector.body
 ;
 ; CHECK: vec.epilog.vector.body:
-; CHECK:   br i1 %12, label %vec.epilog.middle.block, label %vec.epilog.vector.body, !prof [[PROF_F0_VEC_EPILOG_VECTOR_BODY:![0-9]+]]
+; CHECK:   br i1 {{.+}}, label %vec.epilog.middle.block, label %vec.epilog.vector.body, !prof [[PROF_F0_VEC_EPILOG_VECTOR_BODY:![0-9]+]]
 ;
 ; CHECK: vec.epilog.middle.block:
-; CHECK:   br i1 %cmp.n12, label %exit.loopexit, label %vec.epilog.scalar.ph, !prof [[PROF_F0_MIDDLE_BLOCKS:![0-9]+]]
+; CHECK:   br i1 %cmp.n11, label %exit.loopexit, label %vec.epilog.scalar.ph, !prof [[PROF_F0_MIDDLE_BLOCKS:![0-9]+]]
 ;
 ; CHECK: vec.epilog.scalar.ph:
 ; CHECK:   br label %loop